KR101087505B1 - Method and device for manufacturing bolt, screw rolling die used therefor, and multiple screw bolt - Google Patents

Abstract

Provided are a method and a manufacturing apparatus for a bolt capable of mass-producing a multithreaded bolt, such as a so-called double screw bolt, at a lower cost, and a thread rolling die used in the same. It is a manufacturing apparatus of the bolt provided with the pair of screw roll die 1 arrange | positioned at predetermined intervals and the bolt support part 2 which supports the cylindrical bolt material 3 at a predetermined position. The screw roll die 1 has a normal thread part 5, which is a part of the normal thread part that has developed a normal screw, and a normal thread part according to the phase shift between the fine thread and the normal thread represented by the imaginary line 6a that has developed a fine screw. The transfer pattern 4 which consists of the processus | protrusion 6 which is a part of the thin thread 6a periodically formed in the valley part 5a of this is provided.

Thread Rolling Dies, Plain Thread, Fine Thread, Pitch, Phase Shift, Bolt, Corrugated Bottom, Rolling, Thread Height, Rolling Pitch Circle

Description

METHOD AND DEVICE FOR MANUFACTURING BOLT, SCREW ROLLING DIE USED THEREFOR, AND MULTIPLE SCREW BOLT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bolt having a loosening function and a manufacturing apparatus, and screw rolling dies and multi-screw bolts used in the same.

In recent years, various bolts having a loosening function and a manufacturing method thereof have been researched and developed. For example, the bolt described in International Publication No. 02/077466 pamphlet (hereinafter referred to as "Patent Document 1") is a coarse screw thread having a pitch P formed from the tip end portion of the bolt shaft portion to a predetermined portion. Part and fine screw thread of a pitch p (p = P / n, n is an integer of 2 or more) formed at least in the whole threaded portion or the tip end portion of the bolt shaft portion to the predetermined portion of the ordinary thread portion. It is a structure provided with a part.

In this bolt (so-called double-threaded bolt), a coarse nut is screwed onto the normal thread of the bolt, and then a fine nut is superimposed on this thin nut to screw the bolt and the The nut can be tightened. At this time, since the pitch of the thin nut and the common nut is different, when both are united and rotated in the same direction, a repulsive force acts on the contact surface (seat surface) between both nuts, and the nut is prevented from rotating in the loose direction. can do.

Patent Literature 1 also describes a method for producing this double screw bolt. The manufacturing method first forms a normal threaded portion of the pitch P by cutting from the tip end portion of the bolt shaft portion to a predetermined portion, and thereafter, at least the full length of the normal threaded portion of the bolt shaft portion or the small threaded portion of the bolt shaft portion at the tip end thereof. It is usually superimposed on the threaded portion up to the top, and forms a thin threaded portion of the pitch p by cutting.

As described above, first, when the ordinary thread part is formed by cutting, and then the thin thread part superimposed on the normal thread part is formed by cutting, in order to manufacture one double screw bolt, the cutting step is not performed twice. You must. In addition, burrs are formed in the portion which is repeatedly cut when the screw portion is formed to be superimposed on the ordinary screw portion formed by the first cutting and the second cutting is performed. Therefore, the process of removing this bur with a wire brush etc. is required.

In addition, although Patent Document 1 usually mentions manufacturing double-threaded bolts by roll forming in one step using coarse dies and fine dies, As described in Patent Literature 1, even if a normal die and a thin die are disposed to face each other at regular intervals, and a bolt shaft portion is inserted between the ordinary die and the thin die to perform rolling processing, in reality, the double screw bolt is actually used. It is impossible to manufacture. This is because the screw thread rolled by one die (usually a die and a thin die) will be crushed by the other die (a fine die and a normal dice).

In addition, although Patent Document 1 has a description that it can be similarly implemented even if a die formed of a single thread and a thin thread are integrally formed, Patent Document 1 describes how to integrally form a normal thread and a thin thread specifically. It is not. Normally, the description of a die formed by integrally forming a thread and a thin thread seems to be correct at first glance, but in reality, the ordinary thread and the thin thread cannot be integrally formed on one die. It is not possible to manufacture double screw bolts.

Thus, the double-threaded bolt of patent document 1 actually has no choice but to manufacture by cutting. By the way, in the manufacturing method by cutting as mentioned above, since there are more manufacturing processes than a normal bolt, manufacturing cost is extremely high and the unit cost of a double screw bolt is very high.

Then, in this invention, it aims at providing the manufacturing method and manufacturing apparatus of the bolt which can mass-produce multithreaded bolts, such as what is called a double-threaded bolt, at low cost, and the thread rolling die used for this.

In order to solve the above problems, the screw rolling die of the present invention is a part of the ordinary thread that has developed the normal screw, and the bone thread of the ordinary thread is periodically formed in accordance with the phase shift between the fine thread that has developed the fine screw and the normal thread. It is provided with a part of the thin thread formed. The apparatus for manufacturing a bolt of the present invention is a bolt manufacturing apparatus in which a bolt material is pressed against a thread rolling die and plunge rolled, wherein at least one of the screw rolling die is used as the screw rolling die of the present invention. will be. The manufacturing method of the bolt of this invention WHEREIN: The manufacturing method of the bolt which presses a bolt material on a screw rolling die and plunge-rolls, WHEREIN: At least 1 of a screw rolling die is used as the screw rolling die of this invention.

According to the manufacturing method and manufacturing apparatus of the bolt of the present invention, the bolt material is pressurized by a part of the normal thread and a part of the thin thread formed on the thread rolling die, and the outer circumference of the bolt material by the part of the normal thread on the thread rolling die. A portion of the threads that are usually thin on the surface and part of the threads that are thin on a portion of the normal threads on the outer circumferential surface of the bolt material by the portion of the thin threads on the thread rolling die are transferred at once in one step. Thereby, the so-called double threaded bolt in which a part of normal thread and a part of thin thread is formed can be obtained.

Here, the normal screw refers to a screw in which a combination of diameter and pitch is common and most commonly used. In addition, a thin screw is a screw with a narrow ratio of pitch with respect to a diameter compared with a normal screw, and a shallow groove. The pitch of the fine thread about the screw rolling die of this invention should just be below the pitch of a normal thread. The shape of each thread may be any of triangular screws, trapezoidal screws, square screws, toothed screws, round screws, ball screws, other special screws, and the like, and may be arbitrarily combined.

In addition, in this specification, the thing of the cylindrical body or the cone body which has two or more threads which differ in pitch, but differs in pitch on a coaxial is called multiple screw. The multi-screws are double threads when the number of threads with different pitches is 2, double screws when 3, triple screws when 4, quad screws when 4,. If n, n is called the middle screw. When the ratio of the thread of the largest pitch to the thread of the smallest pitch is a to n (a and n are the minimum integer ratios), the multithreaded screw is used for each pitch (a) of the thread of the large pitch. The shape of the thread changes periodically.

In the case of manufacturing double-threaded bolts, the thread rolling dies are a part of the normal thread in which the ordinary thread is unfolded, and a thin thread having a helix in the same direction as the ordinary thread in the valley of the ordinary thread and having a smaller pitch than the ordinary thread (but The ratio of the pitch of a normal screw to a thin screw is a to b, and a and b are the minimum integer ratios.) We shall have a part.

In addition, the screw rolling die is also the finest screw having a smaller pitch than the screw having a spiral in the same direction as the ordinary screw in the valley formed by a part of the normal thread and a part of the thin thread. The ratio of the pitch of the screw to the highest screw is a to b to c and a and b to c are the minimum integer ratios.) By having a part of the finest thread periodically revealed every c winding of the thread, it is possible to manufacture a triple screw bolt in which a part of the normal thread, a part of the thin thread and a part of the finest thread are formed.

In the case of manufacturing an n-thread screw, the thread rolling die has a part of the common thread in which the ordinary thread is unfolded, and a spiral in the same direction as the normal screw in the valley of the ordinary thread, and the pitch is smaller than that of the ordinary thread, and the pitch is smaller. 1 or a plurality of fine screws (however, the ratio of the pitch of a normal screw and a single or a plurality of fine screws is a to… to n, and a,…, n is a minimum integer ratio). In this case, it is assumed to have a part of each thin thread periodically exposed every n windings of the thread as the phase shifts from the normal thread. Thereby, it is possible to manufacture a multi-screw bolt in which a part of a normal thread and a part of each of the plurality of fine threads are formed.

Here, when a part of the thin thread with the smallest pitch among the thin threads develops the thin screw so that the valley bottom when the thin screw is developed becomes a higher position than the bottom of the valley of the normal thread, the phase shift with the normal thread is different. The rolling pitch circle diameter is about half of the bolt height at the bottom of the bone when the thin screw is unfolded. Move inwards. Thereby, the fluctuation | variation of the rolling pitch circle diameter in a process end is reduced, and the fluctuation | variation of the rotation center position of a bolt material is reduced.

At this time, it is preferable that the valley bottom at the time of deploying the narrow screw is 5-50% higher than the height of the narrow thread of the standard standard rather than the valley bottom of the normal thread. Within this range, chatter vibration and noise during processing can be effectively reduced. In addition, when less than 5%, improvement in chatter vibration and noise by changing the valley floor height was hardly seen. On the other hand, if it exceeds 50%, the height of the thin thread of the multi-thread bolt manufactured by the rolling process becomes smaller than the effective diameter of the thin thread of the standard specification, so that the latch of the multi-thread bolt to the thin thread becomes small. .

In addition, when the thread rolling die has a deep groove cut deeper in the bottom of a part of the thin thread, this deep groove serves as a dash pot when rolling multiple screw bolts. Even if the grooves are not completely filled with bolt material, it is possible to produce multi-screw bolts with standard narrow thread dimensions. In addition, by not being fully charged, it is possible to suppress chatter vibration of the processing end that is caused by the full filling as a factor.

At this time, the groove is preferably set to a depth of 3 to 10% of the height of the thin thread of the standard standard. If it is this range, the role of a dash pot can fully be exhibited, the multi-threaded bolt which has a thin thread of a perfect shape can be manufactured, and chatter vibration of a processing end can be fully suppressed. Moreover, when less than 3%, the improvement by installing a groove was hardly seen. On the other hand, if it exceeds 10%, the groove is too deep, which may affect the thin thread shape of the multi-screw bolt.

Here, if the screw rolling die of this invention forms a part of a normal thread and a part of a thin thread on a round die, this screw rolling die is arrange | positioned at predetermined space | intervals, and it rotates in the same direction, respectively, and this screw rolling die A double screw bolt can be manufactured by pressurizing a bolt material to liver.

Moreover, if the thread rolling die of this invention formed a part of a normal thread and a part of a thin thread on a flat die, this thread rolling die will be arrange | positioned at predetermined space | intervals, and fixed one and moving the other in parallel, Alternatively, a double-threaded bolt can be manufactured by moving in parallel to each other in the opposite direction and pressing the bolt material between the screw rolling dies.

In addition, although the screw roll die of this invention should just arrange | position at least 1 among the some thread rolling dice arrange | positioned at a predetermined space | interval, it is also possible to make all the screw roll dies the screw roll die of this invention. In the case where one of the screw rolling dies is used as the screw rolling die of the present invention, the other thread rolling die is a normal ordinary screw die in which only ordinary screws are developed. Moreover, when applying to the manufacturing method or manufacturing apparatus of the bolt of a rotary planetary system, the thread rolling die of this invention may be applied to either one of a round die or a segment die, and may be applied to both.

According to the present invention, the following effects can be obtained.

(1) At least a screw rolling die having a portion of a common thread having a flattened screw thread and a portion of a thin thread periodically formed at a valley of the normal screw thread according to a phase shift between the thin screw having a thin screw laid out and the normal thread. By arrange | positioning one and pressing and plunge-rolling a bolt material to a screw rolling die, a bolt material is pressurized by a part of the normal thread formed on the thread rolling die and a part of a thin thread, and the outer periphery of this bolt material Since a part of the normal thread and a part of the thin thread are transferred at once in one process on the surface, a bolt with a so-called double screw, in which a part of the thread and a part of the thin thread is usually formed, is mass-produced at a lower cost than cutting. It becomes possible.

(2) A part of the common thread which usually unfolds the screw, and a thin screw having a spiral in the same direction as the normal screw in the valley of the common thread and having a smaller pitch than the normal screw (However, the ratio of the pitch of the ordinary screw and the thin screw at least one screw rolling die having a portion of the thin thread periodically exposed every b windings of the normal thread as the phase shifts from the normal thread when a to b and a and b are minimum integer ratios. The bolt material is pressurized by a part of the normal thread formed on the thread rolling die and a part of the thin thread by arranging and pressing the bolt material by pressing the bolt material onto the thread rolling die, and on the outer peripheral surface of the bolt material. Since some of the normal threads and some of the thin threads are transferred in one step at a time, usually some of the threads and some of the thin threads A, it becomes possible to lower step horizontal mass production than the screw bolt cutting of the so-called two.

(3) The finest screw having a smaller pitch than the screw having a spiral in the same direction as the normal screw in the valley formed by a part of the common thread and a part of the thin thread (however, The pitch of the thread is a to b to c, and a, b and c are the minimum integer ratios.) By arranging at least one screw rolling die having a part of the highest screw thread periodically revealed every time, and pressing the bolt material to the plunge rolling process to the screw rolling die, a part of the normal thread formed on the screw rolling die, thin The bolt material is pressurized by a part of the thread and a part of the thinnest thread, and on the outer circumferential surface of the bolt material, Since part of the fine and fine threads and part of the finest threads are transferred in one step at a time, the so-called triple-threaded bolts, usually formed with part of the threads, part of the fine threads and part of the finest threads, are lower than cutting. It is possible to mass produce horizontally.

(4) One or a plurality of fine threads having a pitch that is smaller than a normal thread and has a helix in the same direction as the normal screw in a part of the common thread in which the common screw is unfolded, and the valley of the normal thread, The ratio of the pitch of the screw and the plurality of fine screws is a to ... vs n, and a, ..., n is the minimum integer ratio). By arranging at least one screw rolling die having a portion of each thin thread periodically exposed, and by plunge rolling by pressing bolt material onto the screw rolling die, a portion and a plurality of ordinary threads formed on the thread rolling die are formed. The bolt material is pressurized by a portion of the thin threads of and on the outer circumferential surface of the bolt material a portion of the normal thread and a portion of each of the plurality of fine threads is 1 Since it is transferred at a time by the process, it becomes possible to mass-produce so-called multi-screw bolts in which a part of a thread and a part of each of a plurality of thin threads are formed at a lower cost than cutting.

(5) When a part of the thin thread having the smallest pitch among the thin threads develops the thin screw so that the valley bottom when the thin screw is developed becomes a position higher than the valley bottom of the normal thread, As a result, it is revealed periodically every n windings of the thread, so that the fluctuation of the rolling pitch circle diameter at the end of the machining during the rolling process is reduced, and the fluctuation of the rotational center position of the bolt material is reduced. As a result, the material filling ratio of the screw rolling die to the groove portion becomes more even, and chatter vibration can be greatly suppressed.

(6) When the thread rolling die has a deep groove cut deeper in the valley bottom of a part of the thin thread, when rolling multiple screw bolts, the thread rolling die is not completely filled with the groove of the screw rolling die. Multi-threaded bolts with thin threads of die thin thread height can be produced. In addition, by not being fully charged, chatter vibration of the processing boil generated by full charging as a factor can be suppressed.

(7) The double screw bolt obtained by the rolling process using the screw rolling die of the present invention has a smooth curvature at the distal end portion of the boundary between the normal thread and the thin thread, similar to the double screw bolt manufactured by cutting. Usually, no edges occur at the boundary between threads and fine threads.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the manufacturing apparatus of the double screw bolt in 1st Embodiment of this invention.

FIG. 2 is a perspective view illustrating the screw rolling die of FIG. 1. FIG.

3 is a view in which a part of the transfer pattern of the outer circumference of the screw rolling die of FIG. 2 is developed in a plane.

4A is a cross-sectional view taken along the line A-A of FIG.

4B is a cross-sectional view taken along the line B-B in FIG. 3.

4C is a cross-sectional view taken along the line C-C in FIG.

4D is a cross-sectional view taken along the line D-D in FIG. 3.

4E is a cross-sectional view taken along the line E-E in FIG.

4F is a cross-sectional view taken along the line F-F in FIG. 3.

5A is an enlarged view of a portion of FIG. 4A.

5B is an enlarged view of a portion of FIG. 4D.

FIG. 6A is an enlarged partial view corresponding to FIG. 5A of a screw roll die with a correction; FIG.

FIG. 6B is a partially enlarged view corresponding to FIG. 5B of a screw rolling die with correction. FIG.

FIG. 7A is a partially enlarged view corresponding to FIG. 5A of a thread rolling die with a correction. FIG.

FIG. 7B is a partially enlarged view corresponding to FIG. 5B of a screw rolling die with correction. FIG.

FIG. 8A is a partially enlarged view corresponding to FIG. 5A of a screw rolling die with correction. FIG.

FIG. 8B is a partially enlarged view corresponding to FIG. 5B of a screw rolling die with correction. FIG.

Fig. 9 is a schematic diagram showing an apparatus for manufacturing double screw bolts in a second embodiment of the present invention.

10A, 10B, 10C, 10D, 10E, and 10F are cross-sectional views of a screw rolling die for a triple screw bolt in a third embodiment of the present invention.

11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H are views showing the state of material flow in the cross section along the line A-A in FIG.

12A, 12B, 12C, 12D, 12E, 12F, 12G, and 12H are diagrams showing the state of material flow in the cross-sectional view along the line B-B in FIG.

13A, 13B, 13C, 13D, 13E, 13F, 13G, and 13H are diagrams showing the state of the material flow in the cross section taken along the line D-D in FIG.

(The best mode for carrying out the invention)

(Embodiment 1)

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows the manufacturing apparatus of the double screw bolt in 1st Embodiment of this invention, and FIG. 2 is the perspective view which showed the thread rolling die 1 of FIG.

As shown in FIG. 1, the manufacturing apparatus of the double screw bolt in this embodiment is a pair of screw rolling die 1 arrange | positioned at predetermined intervals, and a cylindrical bolt material (henceforth a "work It is provided with the bolt support part 2 which supports (3) in a predetermined position. In addition, as shown in FIG. 2, the screw roll die 1 forms the transfer pattern 4 for double screw bolt formation in the outer periphery of a cylindrical die (round die).

3 is a plan view of a portion of the transfer pattern 4 of the outer periphery of the screw rolling die 1 of FIG. 2, FIGS. 4A, 4B, 4C, 4D, 4E, and 4F, respectively. 3 are AA line cross section, BB line cross section, CC line cross section, DD line cross section, EE line cross section, and FF line cross section.

As shown in FIG. 3, the transfer pattern 4 corresponding to the double-threaded bolt to manufacture is repeated on the outer periphery of the screw rolling die 1 for 16 pieces per week. The outer diameter of the thread rolling die 1 is 173.987 mm, and the double-threaded bolt is nominal diameter M12, and is usually 1.75 mm in screw pitch and 0.875 mm in fine thread pitch. Therefore, the transfer pattern 4 of one double screw bolt is formed in the range of 22.5 degrees among 360 degrees of the outer periphery of the screw rolling die 1. The A-A line, the B-B line, the C-C line, the D-D line, the E-E line, and the F-F line in FIG. 3 are provided at 3.75 ° intervals, respectively.

As shown in Figs. 4A to 4F, the transfer pattern 4 (shown in solid lines in Figs. 4A to 4F) of the screw rolling die 1 is a standard thread in which a screw is usually developed on the surface of a round die. It consists of a part of the ordinary thread (hereinafter, referred to as a "normally threaded portion") 5, and an additional projection 6 periodically formed on the valley portion 5a of this ordinary thread. The projection 6 has a spiral in the same direction as the original ordinary screw of the expanded normal thread, and has a thin thread (dotted line in Figs. 4A to 4F) that has developed a narrow screw having a smaller pitch than the ordinary thread. Is formed in a periodic shape according to the phase shift (7) between the thread and the normal thread.

Here, when the ratio of the pitch of a normal screw and a thin screw is a to b (however, a and b are the minimum integer ratio. In the example of illustration, it is set as 2 to 1), the projection 6 is a thin screw. As the phase shifts from the normal thread, the b winding of the normal thread becomes a part of the thin thread that is periodically exposed every one winding in the illustrated example. As shown in Figs. 4A to 4F, the imaginary line 6a The thin threads shown in Fig. 3 show only the portions protruding from the normal threads by the phase shift 7 from the normal threads as additional protrusions 6. That is, the protrusions 6 are formed by the fine threads. Rather, it is a projection which additionally protrudes from the normal thread so as to correspond to the imaginary line 6a of the thread that is thinned by the amount of the offset due to the phase shift 7. The ordinary thread portion 5 is the screw rolling die 1. Grinding thread exposed on the surface of the A portion except a portion (a surface of the projection 6).

In addition, in the example shown to FIGS. 4A-4F, the valley bottom 5b of the valley part 5a of the normal thread used as a reference | standard, and the valley bottom of the imaginary line 6a of the thin thread corresponding to the protrusion 6 ( Although the position of 6b) is matched, it is not limited to this.

For example, when the ordinary nut is screwed to the normal thread of the double screw bolt (not shown) manufactured by the screw rolling die 1 in this embodiment, the projection 6 of the screw rolling die 1 The contact area is reduced by the amount of), but by moving the position of the valley bottom 6b of the imaginary line 6a of the thin thread corresponding to the projection 6 to the lower side of FIGS. 4A to 4F, The area of contact between the normal thread and the normal nut can be increased.

Moreover, in the case of a normal screw rolling die, since either one of a normal thread or a thin thread is formed on the surface, a normal screw nut or a thin screw nut can be fitted. However, in the case of the thread rolling die 1 in this embodiment, even if it is going to insert a normal screw nut and a thin screw nut, it does not fit. On the surface of the screw rolling die 1, as described in Patent Literature 1, the conventional ordinary thread and the thin thread are not integrally formed (though the specific structure is not clear), but the ordinary thread part 5 and the ordinary thread. This is because the projections 6 having a periodic shape are formed in the valleys 5a of the original ordinary threads of the section 5.

In order to manufacture a double screw bolt using the manufacturing apparatus of the double screw bolt of the said structure, the cylindrical workpiece | work 3 is arrange | positioned on the bolt support part 2, and this workpiece | work 3 is a pair of screw It presses between the rolling dies 1, and rotates a pair of screw rolling die 1 in the same direction (for example, the right direction as shown by the arrow in FIG. 1). As a result, a double screw bolt in which a part of the normal thread and a part of the thin thread is transferred at once in one step on the outer circumferential surface of the work 3, and a part of the normal thread part and a part of the thin thread part are formed. .

On the outer circumferential surface of the double-threaded bolt thus obtained, grooves (usually corresponding to the threaded portion 5 and the projections 6) of the reverse pattern of the transfer pattern 4 of the screw rolling die 1 of Figs. 4A to 4F. Groove) is formed.

The obtained double screw bolt is a state in which a thin thread is cut out after a normal thread is formed similarly to a double screw bolt formed by conventional cutting. Therefore, the obtained double screw bolt can be fitted with a normal screw nut and a thin screw nut.

In addition, the double screw bolt fits the valley of the normal thread of the ordinary screw nut to the valley of the normal thread of the double screw bolt, Since it is to fit the peak part of the fine thread of a screw nut, it is common to form so that the radial position of the top of a threaded thread may always correspond with the radial position of the top of a thin thread. The projection of the screw roll die for manufacturing such a double-threaded bolt expands the thin screw so that the position of the valley bottom when the thin screw is deployed coincides with the valley bottom position of the normal thread, and is out of phase with the normal thread. As a general rule, it consists of a small number of thin threads that appear periodically every b windings of the thread. Hereinafter, the screw rolling die which has such a process is called "standard dice."

5A and 5B are partially enlarged views of FIGS. 4A and 4D, respectively. As shown in Figs. 5A and 5B, the periodically changing groove depths of the standard dice are usually the positions of the valley bottoms 5b of the threads and the fine threads 6a of the thin screws developed to form the projections 6. The deepest part (AA line cross section) which the position of the valley bottom 6b of () overlaps with each other best, and is shallowest in the part (DD line cross section) where the position of both is shifted most. For this reason, when rolling double-threaded bolts with a standard die, the diameter of the rolling pitch of the tool and the work 3 (the position where the tool and the work 3 are in rolling contact) in the final step of the machining, When viewed from the workpiece 3, it is the largest in the cross section of the AA line and the smallest in the cross section of the DD line.

As a result, the rotation center position of the workpiece 3 always fluctuates at the machining point in time (that is, the final break-in step of machining), which causes severe chatter vibration and noise. Depending on the degree of this chatter vibration, it may cause poor precision, significantly shorten the tool life, and adversely affect the manufacturing apparatus. Moreover, in this standard die, since the cross-sectional area of the groove portion in each cross section is different (that is, the largest in the AA line cross section and the smallest in the DD line cross section), there is a difference in the material filling rate into the groove portion in each cross section. In particular, at the end of processing, since the filling rate of the material into the grooves is high, the free space of the surplus material is lost. This also causes problems such as chatter vibration.

Therefore, in the present embodiment, the protrusions 6 have a normal screw thread when the thin screw is developed so that the valley bottom 6b at the time of developing the thin screw is higher than the valley bottom 5b of the normal thread. It is preferable to set it as a part of the thin thread 6a which periodically appears every b windings of a thread according to phase shift of. At this time, as shown in Figs. 6A and 6B, the thin screw to be developed is a thin screw having a shallower depth of 5 to 50% than the standard standard, and when the thin screw is developed by this shallower amount dh. The valley bottom 6b of the thread is usually higher than the valley bottom 5b of the thread.

Alternatively, as shown in FIG. 7A and FIG. 7B, the thin screw to be expanded is usually the valley of the thin thread 6a of the thin screw that is developed to form the position of the valley bottom 5b of the thread and the protrusion 6. In the part where bottom 6b overlaps best (AA line cross section), the screw becomes 5 ~ 50% shallower than the standard standard, and in the part where both positions are most misaligned (DD line cross section) It shall change smoothly so that it may become the depth of a bone.

When rolling double-threaded bolts using these modified roll rolling dies, the rolling pitch circle diameter in the cross section of the AA line expanded compared to the case of rolling using a standard die. About half of the quantity dh which made the depth of the valley bottom 6b at the time of shallow at the time moves to the inside of the workpiece | work 3, and the quantity approaches the rolling pitch circle diameter in DD line cross section. Therefore, the fluctuation | variation of the rolling pitch circle diameter in a process end is reduced, and the fluctuation | variation of the rotation center position of the workpiece | work 3 is reduced. In addition, since the cross-sectional area of the groove portion of the A-A line cross section becomes closer to the cross-sectional area of the groove portion of the D-D line cross-sectional area, the material filling rate of the groove portion of each cross section becomes more even, and chatter vibration can be greatly suppressed.

On the other hand, in the double screw bolt rolled using the screw rolling die to which such correction has been applied, the mount height of the naturally thin screw portion (especially in the portion corresponding to the A-A cross section) is lower than that of the standard specification. However, since the double-threaded bolts obtain most of the clamping force in the ordinary threaded portions, the static and dynamic fatigue strengths are hardly impaired, and sufficient loosening prevention effect can be exhibited.

By the way, when the double screw bolt is rolled using a screw roll die that has been corrected as described above, problems such as chatter vibration in roll processing using a standard die can be solved. The height of the thin thread is lower than that of the standard standard. However, in consideration of the strength of the thin screw portion, the locked state of the thin screw nut, or the merchandise, the completeness of the mount height of the thin screw portion may be required.

In this case, the screw rolling die is provided with the groove 6c cut deeper in the valley bottom 6b of a part of the fine thread 6a exposed as the projection 6, as shown to FIG. 8A, FIG. 8B. do. The depth dv of this groove 6c is 3 to 10% of the height of the thin thread 6a. When rolling double-threaded bolts by such a thread rolling die, the groove 6c serves as a dash pot, and even if the workpiece 3 is not completely filled by the groove of the screw rolling die, Branches can make double screw bolts. Accordingly, it is possible to suppress chatter vibration of the processing boil, which is caused by the full filling as a factor.

(Embodiment 2)

Fig. 9 is a schematic diagram showing an apparatus for manufacturing double screw bolts in a second embodiment of the present invention.

As shown in FIG. 9, the manufacturing apparatus of the double screw bolt in this embodiment is provided with the pair of screw roll die 8 arrange | positioned opposingly at predetermined intervals. One pair of screw rolling dies 8 is fixed and the other is arranged to be movable in parallel, or arranged to be movable in opposite directions to each other.

The screw rolling die 8 forms the transfer pattern 9 for double screw bolt formation in the single side | surface of the flat dice | dies (flat dice). The transfer pattern 9 expands the same thing as the transfer pattern 4 in 1st Embodiment in the plane.

In order to manufacture a double screw bolt using such a double screw bolt manufacturing apparatus, the cylindrical work piece 3 is pressed between a pair of screw rolling dies 8, and one screw rolling die 8 is pressed. The parallel movement is carried out while keeping parallel with the other screw rolling die 8, or in parallel with each other. Thereby, similarly to the first embodiment, a part of the normal thread and a part of the thin thread are transferred at once in one step on the outer circumferential surface of the work 3, and a part in which a part of the normal thread part and a part of the thin thread part is formed is provided. You can get a heavy thread bolt.

Embodiment 3

10A, 10B, 10C, 10D, 10E, and 10F are cross-sectional views of the screw rolling die 10 for the triple screw bolt in the third embodiment of the present invention.

On the outer circumference of the screw rolling die 10, 16 transfer patterns corresponding to a triple screw bolt to be manufactured are repeatedly formed for one week, and FIGS. 10A to 10F are cross-sectional views of the outer circumference of the screw rolling die 10. Is shown at 3.75 ° intervals.

As shown in Figs. 10A to 10F, in the thread rolling die 10 for the triple screw bolt, it is further developed to the valley 11 formed by the threaded portion 5 and the projection 6, respectively. The finest screw having a helix in the same direction as the original ordinary screw of the common thread and having a smaller pitch than the finer screw which forms the protrusion 6, however, The ratio is a to b to c, and a to b and c are to be the minimum integer ratios. In the example of illustration, the ratio is 4 to 2 to 1). The projection 12 consisting of a part of the highest thread (shown as a dotted line (phase line) 12a in Figs. 10A to 10F) periodically revealed every c winding (one winding in the example) of the thread as the phase shift with )

As shown in Figs. 10A to 10F, the thin thread 6a usually reveals only the portion projecting from the thread as the additional projection 6. Moreover, in this screw rolling die 10, only the part which protruded from this protrusion 6 is revealed as the additional protrusion 12 only the highest threaded thread 12a. The projection 12 is not a thread that is the highest, but is usually the threaded portion 5 so as to correspond to the imaginary line 12a of the thread that is the highest by the amount of the offset due to the phase shift between the normal thread portion 5 and the protrusion 6. And protrusions 6 which are additionally protruding.

In addition, although not shown, when rolling a n-thread screw, it has a part of the normal thread which extended the normal screw, and has a spiral in the same direction as the normal screw, and has a pitch smaller than that of the ordinary screw. Further, one or a plurality of fine screws having different pitches (however, the ratio of pitches of ordinary screws and one or more fine screws is a to ... to n, and a, ..., n is a minimum integer ratio.) In each case, the roll rolling die having projections composed of a part of each thin thread periodically exposed every n windings of the normal thread according to the phase shift with the normal thread may be used.

Moreover, also in the screw rolling die which roll-processes this n-thread screw, it is possible to add correction similarly to the screw rolling die in 1st Embodiment. When correcting the valley depth, when the thin screw is deployed so that the valley bottom when the smallest pitch is developed is higher than the valley bottom of the normal thread, the normal thread is located due to the misalignment with the normal thread. This is to be part of the thin thread that appears periodically every n winding of.

Example 1

The mechanism by which a double screw is transferred to a bolt was analyzed using the manufacturing apparatus of the double screw bolt in 1st Embodiment of the said invention. 11A to 11H, 12A to 12H, and 13A to 13H are diagrams showing the state of material flow in the A-A cross section, the B-B cross section, and the D-D cross section of FIG. 3, respectively. 11A to 11H, 12A to 12H, and 13A to 13H, A to H continuously rotate the distance between each other while rotating a pair of screw rolling dies 1 in the same direction. The state when it narrowed down is shown to the state in which the screw rolling die 1 was finally pushed about 1 mm in the workpiece | work 3 in about 0.1-0.2 mm step.

As shown in FIGS. 11A-11H, 12A-12H, and 13A-13H, as the thread rolling die 1 is gradually pushed into the workpiece | work 3, the workpiece | work 3 is a screw first. Normally, the threaded portion 5a of the thread was filled while plastically deforming along the surface of the ordinary threaded portion 5 of the rolling die 1. And in the situation which filled up to the middle, this time filled the valley part 5a, carrying out plastic deformation along the surface of the projection 6 which protruded normally on the thread. Thereby, the double screw bolt in which a part of normal thread part and a part of thin thread part was formed was obtained.

Example 2

In 1st Embodiment of the said invention, the comparative test of the manufacture of the double screw bolt by the screw roll die which added the correction | amendment and the standard dice | dies was done. Table 1 shows chatter vibration and noise during machining when the depth of the valley bottom 6b of the thin thread and the depth of the groove 6c are changed for the two types of nominal diameters M12 and M16, respectively. It is a result of a measurement. In addition, the pitch ratio of the thread rolling die used for manufacture of the double threaded bolt of M12 is 1.75 to 0.875, and is two to one for M16.

Thread Rolling Dies Type Bone depth Groove depth Chatter vibration noise Standard dice 0% 0% versus versus Crystal Dice 1 5% 0% medium medium Crystal Dice 2 10% 0% small that Crystal Dice 3 20% 0% none that Crystal Dice 4 40% 0% none that Crystal dice 5 0% 5% medium medium Crystal Dice 6 0% 10% medium medium

As can be seen from Table 1, in the thread rolling die modified by changing the depth of the valley bottom 6b of the thin thread, the depth of the valley bottom 6b was made shallower from 5% to 40% with respect to the standard thread. At the time, the shallower the chatter, the lower the chatter vibration and the noise. On the other hand, in the thread rolling die modified by changing the depth of the groove 6c, when the depth of the groove 6c is set to 5% and 10% of the narrow thread height of the standard standard, Improvement was confirmed.

In addition, all these thread rolling dies passed the loosening test by the American Aviation Standard NAS3354 Vibration Test Method. In addition, it was confirmed that the static strength test by the Amsler tensile strength test method and the dynamic strength test by the hydraulic servo test method had the same capability as the standard screw bolt.

The present invention is useful when a multi-threaded bolt having a loosening function is produced by rolling.

Claims (16)

In the manufacturing method of the bolt which presses a bolt material to a screw rolling die and plunge-rolls it, At least one of the screw rolling dies has a peak portion of a common thread in which the ordinary screw is deployed, and a thin screw having a spiral in the same direction as the ordinary screw in the valley portion of the ordinary thread and having a smaller pitch than the ordinary screw ( The ratio of the pitch of the screw to the thin screw is a to b, and a and b are the minimum integer ratios.) The valley bottom is 5 to 50% higher than the standard narrow thread height than the valley bottom of the normal thread. And a projection corresponding to a thin thread periodically exposed at every b winding of the normal thread as the phase shifts from the normal thread when deployed to a position. In the manufacturing method of the bolt which presses a bolt material to a screw rolling die and plunge-rolls it, At least one of the thread rolling dies has a peak portion of a common thread in which an ordinary screw is deployed, and a valley in the valley of the ordinary thread having a spiral in the same direction as the ordinary screw and having a smaller pitch and a different pitch than the ordinary screw, or When a plurality of fine screws (however, the ratio of the pitch of the ordinary screw and the one or the plurality of fine screws is a to ... to n, and a, ..., n are the minimum integer ratios) However, for the finest thread with the smallest pitch, when the bottom of the bone is developed to be 5-50% higher than the standard thread height of the standard thread above the bottom of the normal thread, And a projection corresponding to each thin thread periodically exposed every n windings of the normal thread. delete delete In the manufacturing apparatus of the bolt which presses a bolt material to a screw rolling die and performs plunge rolling, At least one of the screw rolling dies has a peak portion of a common thread in which the ordinary screw is deployed, and a thin screw having a spiral in the same direction as the ordinary screw in the valley portion of the ordinary thread and having a smaller pitch than the ordinary screw ( The ratio of the pitch of the screw to the thin screw is a to b, and a and b are the minimum integer ratios.) The valley bottom is 5 to 50% higher than the standard narrow thread height than the valley bottom of the normal thread. A device for manufacturing a bolt, comprising a projection corresponding to a thin thread periodically exposed at every b winding of the normal thread as the phase shifts from the normal thread when deployed to a position. In the manufacturing apparatus of the bolt which presses a bolt material to a screw rolling die and performs plunge rolling, At least one of the screw rolling dies has a peak portion of a common thread in which the ordinary thread is deployed, and a valley in the valley of the ordinary thread, having a spiral in the same direction as the ordinary screw, and having a smaller pitch and a different pitch than the ordinary thread, or When a plurality of fine screws (however, the ratio of the pitch of the ordinary screw and the one or the plurality of fine screws is a to ... to n, and a, ..., n are the minimum integer ratios) However, for the finest thread with the smallest pitch, when the bottom of the bone is developed to be 5-50% higher than the standard thread height of the standard thread above the bottom of the normal thread, And a projection corresponding to each thin thread periodically exposed every n windings of the normal thread. delete delete A thin screw having a helix in the same direction as the normal screw and having a spiral in the same direction as that of the normal screw, and a pitch of the normal thread which has unfolded the normal screw (but the ratio between the pitch of the normal screw and the fine screw) Is a to b, and a and b are the minimum integer ratio.) The ordinary thread is developed when the valley bottom is positioned 5 to 50% higher than the standard thread fine thread height above the valley bottom of the normal thread. A screw roll die having a projection corresponding to a thin thread periodically exposed every b windings of the common thread as a phase shift with the. A plurality of fine screws having a helix in the same direction as the ordinary screw and having a smaller pitch than the ordinary screw and having a different pitch than the ordinary screw, provided that the normal screw has a flattened thread and the valley of the normal screw When the ratio of the pitches of the plurality of fine screws is a to ... to n, and a, ..., n are the minimum integer ratios, respectively (but, for the finest screw with the smallest pitch, the valley bottom is described above). On the thin thread, which is periodically exposed at every n windings of the normal thread, as the phase shifts from the normal thread. Screw rolling die which has a corresponding projection. delete delete The multi-threaded bolt of the screw rolling die according to claim 9, wherein the bolt material is pressed and plunge rolled. The multi-threaded bolt of the screw rolling die according to claim 10, wherein the bolt material is pressed and plunge rolled. delete delete

Images